[Intel-devsys] irmx-80 diskettes

Herb Johnson hjohnson at retrotechnology.com
Fri Aug 16 16:45:32 MDT 2019

Bill Beech's email of Aug 16 12:40 MDT, had an attached photo of one of 
the physical paper labels on one 8-inch iRMX-80 diskette. The attachment 
did not make the intel-devsys list archive of course. The text on the 
label (I have reasons for posting this) says:

RMX/80 tm Real-Time Multitasker
Executive for iSBC 80/10
single density diskette
part no. 9500018-03 version 1.3
(C) Intel Corporation 1978
[copyright notice on Intel's software license, etc.]

If all of BIll's V1.3 diskettes are single density, then they aren't 
M2FM double density. Many kinds of floppy controllers can read SD. And, 
the disk capacity is only 250Kbytes  or thereabouts; very manageable.

Bill, any of your CP/M 8-inch systems (if working) could read SD 8" 
disks at the track/sector level. The CP/M program "DU" or "DUU" will let 
you examine individual sectors, I'd bet on that.

A simple-enough disk copy program in ASM, could be modified to 
read-a-track of sectors, write-to-serial. Jack's USB program, may 
already do that, write-to-USB of course. Bill said recently, he bought 
some of those serial-USB-drive dongles from the UK.

I just sent you, Bill, CPMUG disk #1 as ZIPped files, which contains an 
ISIS dir program and an ISIS read-file program. You may be able to 
"kermit" files from your CP/M system to a modern computer.

Possibly, some modified read-ISIS-disks-raw program under ISIS, can be 
cajoled to read the iRMX disk on Bill's ISIS system, extract files.

I'm looking at the irmx-80 V2.4 files from Mark Ogden....no 
disk-handling source files. Ditto, V4.0. No obvious help there, can't 
run those iRMX binary programs!


page A-26, section A.6 Flexible Diskette formats

for iRMX I and iRMX II (8086 based), table A-1 says for 8-inch:

sector  density sect/track
128	single	26	
256	single	15	
512	single	8
1024	single	4
256	double	26
512	double	15
1024	double	8

page A-1, section A-1 "Structure of a named volume"

(again - this is iRMX-86 documentation.) Describes at an absolute byte 
number from 0, the format of named volumes. The concept is "fnodes", a 
root directory, space for a bootstrap loader, and some volume labels, a 
pool of fnodes (blocks of storage). There's hints of diskette methods 
(the iRMX volume label is in sector 4 of a single density flexible 

This gets busy fast.

My suggestion to Bill: just image the whole damn diskette, every sector. 
It's only  256Kbytes total. Let other folks figure out how to peel off 
the files from a saved image. With luck, Mark Ogden or someone, has a 
irmx-86 (or -80) file extractor already in hand. Recovering the disk 
image is the essential work, "only the wearer knows where the shoe 
rubs". And recovering the bootstrap loader would be a good thing; I 
don't know if the other irmx-80's have such a recovery.

Hope this helps.

Regards, Herb

On 8/16/2019 5:40 PM, Jack Mcmullen wrote:
> Hi Bill and all,
> The USB Imager/Creater is a direct SBC202 communicator. Was the only way 
> on my side I could do an image. Understand your other hardware. Thought 
> all of us had at least that basic configuration for 80/85 stuff. USB 
> file movement tools goes thru ISIS.
> Jack 
Herbert R. Johnson, New Jersey in the USA
http://www.retrotechnology.com OR .net
preserve, recover, restore 1970's computing
email: hjohnson AT retrotechnology DOT com
or try later herbjohnson AT retrotechnology DOT info

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